Exemplary embodiments of the present invention relate to an exhaust gas distributor for an exhaust gas system of an internal combustion engine, in particular of a motor vehicle.
U.S. Pat. No. 6,422,217 B1 discloses an exhaust gas distributor with a distributor housing defining a first exhaust gas path, a second exhaust gas path, and a third exhaust gas path. The first exhaust gas path fluidically connects a first inlet opening, associated with at least one cylinder of the internal combustion engine, to a first outlet opening associated with a turbine of an exhaust gas turbocharger. The second exhaust gas path fluidically connects a second inlet opening, associated with at least one cylinder of the internal combustion engine, to a second outlet opening associated with the turbine. The third exhaust gas path fluidically connects the second exhaust gas path to a third outlet opening associated with an exhaust gas cooler. The known exhaust gas distributor also includes an adjustable control element for controlling the distribution of an exhaust gas flow, coming from the second inlet opening, over the second outlet opening and the third outlet opening. In the process, the control element in its end positions cooperates with stop contours, and is supported in a control housing manufactured separately from the distributor housing and which is installed in the distributor housing. In the known exhaust gas distributor, the control element is designed as an adjustable-stroke valve element, which in its end positions cooperates with valve seats that form the above-mentioned stop contours. One valve seat is formed on the control housing, while the other valve seat is formed on the distributor housing. To allow cooperation with the valve seat which is formed on the distributor housing, the valve element must be axially extended from the control housing.
The manufacture of an exhaust gas distributor of this type is fairly complicated, since comparatively narrow manufacturing tolerances must be observed so that the valve element may be properly adjusted between its end positions and may properly cooperate with the valve seat which is formed on the distributor housing.
German patent document DE 10 2008 064 264 A1 discloses another exhaust gas distributor that is used to supply the exhaust gases of the internal combustion engine to an exhaust gas turbocharger via dual ducts, whereby exhaust gas recirculation branches off from only one of the two ducts, while the other duct passes undisturbed to the turbine of the exhaust gas turbocharger.
Exemplary embodiments of the present invention provide an improved embodiment of an exhaust gas distributor of the type mentioned at the outset, which is characterized in particular by simplified, preferably inexpensive, manufacture.
In accordance with the present invention all stop contours, with which the control element cooperates in its end positions, are formed directly on the control housing. As a result, it is not necessary to form a stop contour on the distributor housing. Therefore, the distributor housing may be manufactured completely separately from the control element. Due to the integration of all stop contours into the control housing, it is necessary only to manufacture the control housing in combination with the control element, taking appropriate tolerances into account. However, this is achievable in a relatively simple manner, since the dimensions of the control housing are much smaller than those of the distributor housing. In addition, this means no additional expenditures for manufacturing the control housing, whether one stop contour or two stop contours must be provided in light of narrow manufacturing tolerances. The proposed design allows the control element together with the control housing to be configured as a completely pre-assembled unit which is also fully functional, since the control element is adjustable in the control housing between its end positions. In particular, the assembly unit thus formed may also be checked outside the distributor housing for proper functioning.
According to one advantageous embodiment, the control element and the control housing may thus be coordinated with one another in such a way that the control element in all its positions remains within the control housing. In other words, no interactions between the control element and the distributor housing are necessary for the functioning of the control element, which simplifies the separate manufacture of the control housing and the distributor housing.
In one advantageous embodiment, the control element may be situated so as to be pivotably adjustable about a pivot axis oriented transversely with respect to the flow direction of the exhaust gas in the control housing, the control housing being inserted into the distributor housing parallel to this pivot axis. As a result of this design, an assembly unit in which the pivotably adjustable control element remains within the control housing and all stop contours are formed directly on the control housing may be achieved in a particularly simple manner.
According to another advantageous embodiment, the distributor housing may have a receptacle having a receiving opening, situated on an outer side of the distributor housing, through which the control housing is inserted into the receptacle. The distributor housing may thus be prepared in a particularly simple manner for installation of the control housing. It is also noteworthy that, with regard to the distributor housing, it is necessary only to prepare for the accommodation of the control housing. Additional measures for achieving adjustability of the control element, such as coupling to a drive, may be omitted with regard to the distributor housing, which simplifies manufacture of the distributor housing.
According to one advantageous refinement, a flange of the control housing may close the receiving opening in the distributor housing and be fastened to the distributor housing. This type of flange is customarily composed of a circumferential collar that is closed in the peripheral direction, protrudes in the radial direction, and may be screwed to the distributor housing. Such a flange may cover radial play between the control housing and an inner wall of the receiving opening, and may provide sealing with respect to the outside. Manufacture of the exhaust gas distributor is simplified in this way.
In another refinement, the receiving opening may be situated on the same side of the distributor housing as the inlet openings. As a result, the accommodation of the control housing in the distributor housing is not provided externally, so that the exhaust gas distributor as a whole requires no more installation space than an integrated version in which the control element is directly situated or mounted in the distributor housing.
According to another advantageous embodiment, the control housing may be a monolithic cast part. Additionally or alternatively, it may be provided that the distributor housing is a monolithic cast part. Cast parts may be produced with comparatively high precision in large numbers, with relatively low manufacturing costs.
In another advantageous embodiment, the control element may be a valve, in particular a butterfly valve. These types of valve elements have consistently proven satisfactory in practice, and can be manufactured in a comparatively simple and cost-effective manner.
In another advantageous embodiment, it may be provided that in the installed state of the exhaust gas distributor the first inlet opening and the second inlet opening are situated directly on a cylinder head of an internal combustion engine. For example, for this purpose the distributor housing may have a first inlet flange encompassing the first inlet opening, and a second inlet flange encompassing the second inlet opening, the two inlet flanges being flange-mounted on the cylinder head of the internal combustion engine. The exhaust gas distributor thus forms an exhaust manifold or a central component of such an exhaust manifold. An “exhaust manifold” defines the inlet side of an exhaust gas system, and is directly connected to the cylinder head in order to accommodate the exhaust gases of the cylinders exiting at that location at outlet openings associated with the individual cylinders. The exhaust gas distributor presented here may now form such an exhaust manifold or a central component of the exhaust manifold, whereby a turbine of an exhaust gas turbocharger may be directly flange-mounted on the exhaust gas distributor.
According to another advantageous embodiment, each inlet opening in the exhaust gas distributor may be associated with exactly one cylinder of the internal combustion engine. If the exhaust gas distributor for an internal combustion engine is provided with more than two cylinders, the exhaust gas distributor or its distributor housing may have at least one connecting opening via which a manifold, which is fluidically connected to at least one further inlet opening that is associated with a further cylinder, is connectable to the distributor housing. Two such connecting openings are preferably formed on the distributor housing, so that two such manifolds are connectable to the distributor housing. As a whole, this results in an exhaust manifold which has the exhaust gas distributor presented here in a central position, and which includes two such manifolds which are laterally connected to the exhaust gas distributor.
According to another advantageous embodiment, the first outlet opening in the distributor housing may be associated with a first inlet of a dual-duct turbine of an exhaust gas turbocharger, while the second outlet opening in the distributor housing is associated with a second inlet of the dual-duct turbine. Due to this design, a first duct of the turbine is continuously supplied with exhaust gas via the first exhaust gas path, while a second duct of the turbine is acted on by an exhaust gas flow which fluctuates as a function of the desired exhaust gas recirculation. These types of dual-duct turbines are also referred to as twin scroll turbines.
Further important features and advantageous of the invention result from the drawings, and the associated description of the figures with reference to the drawings.
It is understood that the features mentioned above and to be explained below may be used not only in the particular stated combination, but also in other combinations or alone without departing from the scope of the invention.